黄土性土壤剖面中N_2O排放的研究初报

IN-SITU MEASUREMENT OF N_2O EMISSIONS FROM PROFILE OF LOESS SOIL

用田间原位土壤探头测定法和乙炔抑制未扰动土柱法 ,对黄土性土壤N2 O的排放进行了研究。试验结果表明 ,黄土性土壤N2 O的排放量存在着明显的季节和空间变异。季节变化与田间水分因子密切相关 ,N2 O高峰常出现在灌水 (降水 ) 3天后 ,施肥处理和对照的趋势完全一致。全年中八月份各土层N2 O浓度最高 ;在最高峰值时 ,施肥处理的N2 O浓度几乎是对照处理的 2 .5倍。土壤剖面中N2 O的浓度的顺序是 1 0cm <30cm <1 50cm <90cm <60cm ,以 60～90cm土层最高。影响黄土性土壤反硝化的主要因子是作为微生物能源和碳源的有机物质 ,在碳源充足时 ,土壤的硝态氮含量和水分因子是限制因子。

Field soil bores measurement and static C 2H 2 inhibition soil cores method was used to study N 2O emission in the loess soil profile and the factors affecting its production. Significant spatial variation and temporal variation of the nitrous oxide amount were found in the soil used. The temporal variation was correlated with the water supply (such as rainfall or irrigation), and N 2O peaks were occurred 3 days after water events. Both the control and fertilized plots have the same trend. August was the highest N 2O production month during the period. At the highest point the N 2O concentration in the fertilized plot was 2.5 times higher than that in the control plot. Meanwhile N 2O spatial variation in the profile followed the order : 10cm<30cm<150cm<90cm<60cm. Carbon was the limited factor that controled denitrification in the soil. When carbon was supplied, nitrate content and water became the limited factors.